The development of non-invasive assays for diagnosing certain types of cancer has provided practitioners with some options for diagnosis of cancer and other related disease without the need for tissue biopsy. However, such options are limited in their applications and effectiveness. The most definitive test for cancer or related disease is still tissue biopsy. Tissue biopsy occurs when a sample of tissue from a site that is believed to be diseased is harvested and analyzed by a pathologist to determine the nature of the tissue and whether it is healthy tissue, benign tissue growth, or cancerous tissue. Tissue samples from small organs or glands, like lymph nodes or thyroid glands, are especially difficult to harvest due to the relatively small size of the organs or glands (and their respective growths or nodules), location in sites that are uncovered by everyday clothing, and proximity to significant blood vessels. Furthermore, vascularization in many glands or organs is considerable, making the possibility of bleeding a significant issue.
Processes for harvesting a tissue sample from a patient includes three types of procedures. First, open surgery occurs when a patient is cut open to expose the tissue from which a sample is required. The procedure is invasive and creates a considerable risk of infection and side effects as compared to less-invasive procedures. Of the three procedures for biopsy, it is generally considered the least desirable. The second procedure uses a core tissue biopsy needle. A core tissue biopsy needle requires removal of a relatively large piece of tissue from the desired tissue site. The tissue sample is large enough that it requires further processing, including slicing of the tissue sample to analyze under a microscope. An example of a core biopsy device is disclosed in U.S. Pat. No. 4,177,797. The apparatus comprises an improved rotary biopsy device for extracting biopsy samples and the like from specific specimen extracting sites. The '797 patent indicated, in 1977, that a problem in the biopsy field was that prior biopsy devices had not been successful in providing high quality extracted specimens while at the same time minimizing trauma to the patient and providing easy removability of the specimen from the patient. U.S. Pat. No. 5,005,585 discloses a core biopsy needle construction that has an elongated needle member with a sharp annular interior edge. At the time of its filing, the '585 patent commented on the state of the art as follows, “In the past, biopsy procedures have been carried out using a hollow needle of varying internal diameter with a tapered distal end and a diagonal cutting edge . . . . Although biopsy needles of this construction have met with success, failure to obtain an adequate core biopsy specimen frequently occurs. Not infrequently, biopsy specimens will be left behind . . . thus necessitating the need for attempting another pass at obtaining a core biopsy.”
Another technique for harvesting tissue is fine needle aspiration (FNA). Fine needle aspiration removes smaller samples of biopsy tissue that can typically be viewed under a microscope without tissue slicing. The FNA procedure is as follows. A patient is given a local anesthetic. A needle (typically a 20-30 gauge needle) is inserted hypodermically and positioned to the site of the targeted tissue. The needle often penetrates fat tissue and muscular tissue depending on the location of the targeted tissue. The organ or gland is held stationary relative to the movement of the needle. Then, the needle is gently moved into the tissue, thereby causing the needle to take a thin sample of the tissue. The tissue is drawn into the needle either by aspiration or by the capillary action of the needle. Aspiration occurs with the use of a vacuum source such as a syringe. To aid in harvesting an adequate sample size, the needle is optionally moved in and out of the puncture site from about one to five times. This reciprocating motion causes cellular material to be scraped from the tissue and drawn into the needle. Then, the needle is withdrawn from the patient and the tissue collected in the needle is placed on a slide for pathological analysis. Since the individual tissue specimens are smaller/thinner than a core biopsy, no additional tissue slicing is required. The sample can be placed on a slide, stained, and analyzed. Often, with current FNA needles, the process is repeated to obtain between eight and eighteen slides with tissue samples.
U.S. Pat. No. 6,908,440 discloses a fine needle aspiration system with a first sharp edge at the beveled distal end of the needle that scrapes tissue during proximal to distal travel of the needle. The '440 patent discusses a drawback of fine needle aspiration: “[T]he FNA [fine needle aspiration] biopsy needle procedure fails to collect a sample of sufficient size to enable definitive pathological results. When this happens, the physician must repeat the procedure causing additional trauma to the body part undergoing biopsy and creating additional risk of an adverse event.” Additionally, Kim et al., “US-guided Fine-Needle Aspiration of Thyroid Nodules: Indications, Techniques, Results,” RadioGraphics, Volume 28, Number 7, pp. 1869-1899 (November 2008), is a review of current FNA results using ultrasound (US) versus palpation techniques. Despite many proposed designs for biopsy needles, standard hypodermic needles having a size of between 20 and 30 gauge are still the industry standard. Kim concludes, “[h]owever, the achievement of optimal results of the thyroid FNA, with increased efficacy and decreased inadequacy results, requires not only a skillful aspiration technique and attention to the factors that affect material adequacy but also awareness of the indications for and limitations of FNA biopsy . . . . US-guided FNA yields an inadequate specimen in 10%-20% of procedures . . . . ”